DNVGL-OS-C105 Structural Design Of TLPs - LRFD Method
OFFSHORE STANDARDDNVGL-OS-C105Edition July 2015Structural design of TLPs - LRFD methodThe electronic pdf version of this document found through http://www.dnvgl.com is the officially binding version.The documents are available free of charge in PDF format.DNV GL AS
FOREWORDDNV GL offshore standards contain technical requirements, principles and acceptance criteria related toclassification of offshore units. DNV GL AS July 2015Any comments may be sent by e-mail to rules@dnvgl.comThis service document has been prepared based on available knowledge, technology and/or information at the time of issuance of this document. The use of thisdocument by others than DNV GL is at the user's sole risk. DNV GL does not accept any liability or responsibility for loss or damages resulting from any use ofthis document.
GeneralThis document supersedes DNV-OS-C105, July 2014.Text affected by the main changes in this edition is highlighted in red colour. However, if the changesinvolve a whole chapter, section or sub-section, normally only the title will be in red colour.On 12 September 2013, DNV and GL merged to form DNV GL Group. On 25 November 2013 Det NorskeVeritas AS became the 100% shareholder of Germanischer Lloyd SE, the parent company of the GL Group,and on 27 November 2013 Det Norske Veritas AS, company registration number 945 748 931, changed itsname to DNV GL AS. For further information, see www.dnvgl.com. Any reference in this document to “DetNorske Veritas AS”, “Det Norske Veritas”, “DNV”, “GL”, “Germanischer Lloyd SE”, “GL Group” or any otherlegal entity name or trading name presently owned by the DNV GL Group shall therefore also be considereda reference to “DNV GL AS”.Main changes GeneralThe revision of this document is part of the DNV GL merger, updating the previous DNV standard into aDNV GL format including updated nomenclature and document reference numbering, e.g.:— Main class identification 1A1 becomes 1A.— DNV replaced by DNV GL.— DNV-RP-A201 to DNVGL-CG-0168. A complete listing with updated reference numbers can be found onDNV GL's homepage on internet.To complete your understanding, observe that the entire DNV GL update process will be implementedsequentially. Hence, for some of the references, still the legacy DNV documents apply and are explicitlyindicated as such, e.g.: Rules for Ships has become DNV Rules for Ships. Ch.2 Sec.1 Structural categorisation, material selection and inspection principles— [2] More clear definition of structural categories have been provided.— [3.1] Special considerations have been added for casting material.— [3.2] Design temperature definition to be aligned with other OS has been updated. Ch.2 Sec.2 Design principles— [2.1] Better definition of class scope with respect to temporary phases has been provided.— [2.3] Considerations/guidance notes for tendon fabrication have been added.— [2.6] Considerations have been added for VIV/VIM during tendon free standing phase.— [3] Better definition of tendon design principal, guidance note have been added to explain 'fail proof'philosophy.— [4] Design principles for foundation have been added.— [5] Design principles for systems have been added - special consideration for TLP application.— [6] Design principles for simultaneous operations have been added. Ch.2 Sec.3 Design loads— [2] Guidance note has been added with regards to minimum sea pressure. Ch.2 Sec.4 Global performance— [1] More clear definition of design conditions to be considered. Ch.2 Sec.5 Ultimate limit states (ULS)— [1.1.8] Reference has been added for material factors for foundation under ULS condition.— [1.2.6] Guidance note has been added with regards to inclining test requirement for TLP.Offshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 3Changes – currentCHANGES – CURRENT
Ch.2 Sec.7 Accidental limit states (ALS)— [1.2] Guidance note has been added with regards to ballast system capacity.— [2] More clear definition has been provided with respect to accidental loads required in the design.— [3] Requirement of analysis to evaluate consequence of tendon failure has been deleted.— [4] Reference has been added for material factors for foundation under ALS condition. Ch.3 Sec.2 Certification of tendon system— [1] List of acceptable standards have been deleted and reference is made to Table 1-1 and 1-2.— [4] Definition of IRN has been deleted because this is no longer issued; certification for sub-componentsis clarified.— [5.2] Guidance note has been updated to clarify requirements for line pipes.— [5.5] Previous sub-section about Foundation has been deleted; relevant requirements are moved torelevant sections in Chapter 2. Because all the requirements are related to main class design approvalrather than certification or fabrication.— [5.7] Some requirements for tendon tension monitoring system (TTMS) that were accidentally deletedhave been reinstated.— [5.8] Acceptance criteria for tendon porch has been added.— [5.10] Requirements for load management program (LMP) has been further clarified.— [6] Categorization of tendon components, sub-components and their certificate requirements have beenclarified.— [7] Guidance note has been added with regards to level of NDT for tendon pipes.Editorial correctionsIn addition to the above stated main changes, editorial corrections may have been made.Offshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 4Changes – current— [6] Foundation design section has been updated with more detailed requirements.
CHANGES – CURRENT . 3CH. 1 INTRODUCTION . 8Sec.1Introduction . 81General .81.1 Introduction.81.2 Objectives .91.3 Scope and application .92References.103Definitions .113.1 Verbal forms . 113.2 Terms . 114Abbreviations and symbols .124.1 Abbreviations . 124.2 Symbols . 135Description of the tendon system .135.1 General . 13CH. 2 TECHNICAL CONTENT . 16Sec.1Sec.2Structural categorisation, material selection and inspection principles . 161Introduction .161.1 General . 162Structural categorisation .162.1 General . 163Material selection .183.1 General . 183.2 Design temperatures. 184Fabrication inspection categories .184.1 General . 18Design principles. 201Introduction .201.1 General . 202Design conditions .202.1 General . 202.2 General fabrication . 212.3 Tendon fabrication . 212.4 Hull and deck mating . 212.5 Sea transportation . 212.6 Installation . 212.7 Decommissioning . 223Design principles, tendons.223.1 General . 22Offshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 5ContentsCONTENTS
Sec.4Sec.5Sec.6Design principles, foundations.235Design principles, systems .236Design principles, simultaneous operation .24Design loads. 251General .252Load categories .252.1 General . 25Global performance . 271Introduction .271.1 General . 272Frequency domain analysis.272.1 General . 272.2 High frequency analyses . 282.3 Wave frequency analyses . 282.4 Low frequency analyses. 283Time domain analyses .293.1 General . 294Model testing .304.1 General . 305Load effects in the tendons.305.1 General . 30Ultimate limit states (ULS) . 311Introduction .311.1 General . 311.2 Stability . 312Hull.322.1 General . 322.2 Structural analysis . 332.3 Structural design . 333Deck .333.1 General . 333.2 Air gap . 334Scantlings and weld connections .344.1 Scantlings . 344.2 Weld connections. 345Tendons .345.1 Extreme tendon tensions . 345.2 Structural design of tendons . 356Foundations .356.1 General . 356.2 Piled foundations . 366.3 Gravity based foundations . 36Fatigue limit states (FLS) . 371Introduction .371.1 General . 37Offshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 6ContentsSec.34
Sec.7Hull.373Deck .374Tendons .374.1 General . 375Foundation .39Accidental limit states (ALS) . 401General .401.1 General . 401.2 Stability . 402Hull and deck .413Tendons .413.1 General . 414Foundations .41CH. 3 CLASSIFICATION AND CERTIFICATION. 42Sec.1Classification. 421Sec.2General .421.1 Classification. 421.2 Introduction. 421.3 Application. 421.4 Documentation. 42Certification of tendon system . 431Introduction .432Equipment categorization .433Fabrication record .444Documentation deliverables for certification of equipment.445Tendon systems and components .455.1 General . 455.2 Tendon pipe. 465.3 Bottom tendon interface (BTI) . 465.4 Flex bearings . 475.5 Top tendon interface (TTI) . 475.6 Intermediate tendon connectors (ITC) . 485.7 Tendon tension monitoring system (TTMS). 485.8 Tendon porch . 485.9 Tendon corrosion protection system . 485.10 Load management program . 496Categorization of tendon components .497Tendon fabrication.49Offshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 7Contents2
SECTION 1 INTRODUCTION1 General1.1 Introduction1.1.1 This standard provides requirements and guidance to the structural design of TLPs. Therequirements and guidance documented in this standard are generally applicable to all configurations oftension leg platforms.1.1.2 This standard is based on the load and resistance factor design method (LRFD). LRFD is defined inDNVGL-OS-C101.1.1.3 A TLP can alternatively be designed according to working stress design principles, which is definedin DNVGL-OS-C201.1.1.4 A TLP can also alternatively be designed to API RP 2T as it has been accepted that it meets the safetylevels required by this Standard. For requirements that are not specifically defined in API RP 2T, applicablerequirements stated in this offshore standard shall be followed.1.1.5 A Tension Leg Platform (TLP) is defined as a buoyant unit connected to a fixed foundation (or piles)by pre-tensioned tendons. The tendons are normally parallel, near vertical elements, acting in tension,which usually restrain the motions of the TLP in heave, roll and pitch. The platform is usually compliant insurge, sway and yaw. Figure 1 shows an example of a tension leg platform.Offshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 8Chapter 1 Section 1CHAPTER 1 INTRODUCTION
Chapter 1 Section 1Figure 1 Example of a tension leg platform1.1.6 The standard has been written for general world-wide application. Governmental regulations mayinclude requirements in excess of the provisions of this standard depending on size, type, location andintended service of the offshore unit/installation.1.2 ObjectivesThe objectives of the standard are to:— provide an internationally acceptable standard of safety by defining minimum requirements forstructural design of TLPs— serve as a contractual reference document for suppliers and purchasers— serve as guidance for designers, suppliers, purchasers and regulators— specify procedures and requirements for TLP units subject to DNV GL verification classification andcertification services.1.3 Scope and application1.3.1 A TLP is usually applied for drilling, production and export of hydrocarbons. Storage may also be aTLP function.1.3.2 The TLP unit should also be designed for transit relocation, if relevant.Offshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 9
1.3.4 Requirements concerning riser systems are given in DNV-OS-F201.1.3.5 In case of application of a catenary or taut mooring system in combination with tendons, referenceis made to DNVGL-OS-E301. Combined effects of mooring system (e.g. backline moorings) and tendonsystems should be properly accounted for in the design.1.3.6 Requirements related to stability (intact and damaged) are given in Ch.2 Sec.5 for ULS condition andCh.2 Sec.7 for ALS condition.2 ReferencesDNVGL/DNV Offshore Standards and DNVGL/DNV recommended practices in Table 1 and other recognizedcodes and standards in Table 2 are referred to in this standard.Other recognised standards may be applied provided it can be demonstrated that they meet or exceed thelevel of safety of actual DNVGL Offshore Standards.Table 1 DNVGL and DNV reference documentsReferenceTitleDNVGL-OS-A101Safety principles and arrangementDNVGL-OS-B101Metallic materialsDNVGL-OS-C101Design of offshore steel structures, general (LRFD method)DNVGL-OS-C103Structural design of column stabilised units (LRFD method)DNVGL-OS-C106Structural design of deep draught floating UnitsDNVGL-OS-C201Structural design of offshore units (WSD method)DNVGL-OS-C301Stability and watertight integrityDNVGL-OS-C401Fabrication and Testing of offshore structuresDNV-OS-C501Composite ComponentsDNV-OS-C502Offshore Concrete StructuresDNVGL-OS-D202Instrumentation and telecommunication systemsDNVGL-OS-E401Helicopter decksDNVGL-OS-E301Position mooringDNV-OS-F101Submarine Pipeline SystemDNV-OS-F201Dynamic RisersDNV-RP-B401Cathodic Protection DesignDNVGL-RP-C103Column-stabilised unitsDNVGL-RP-C201Buckling of plated structuresDNV-RP-C202Buckling Strength of ShellsDNVGL-RP-C203Fatigue strength analysisDNV-RP-C204Design against Accidental LoadsDNV-RP-F201Composite RisersDNV-RP-F203Riser InterferenceDNV-RP-F204Riser FatigueDNVGL-RP-0001Probabilistic methods for planning of inspection for fatigue cracks in offshorestructuresDNV Classification Notes 30.1 Sec. 2 Buckling Strength Analysis (Bars and Frames)DNV Classification Notes 30.6Structural Reliability Analysis of Marine StructuresDNV-OS-H101Marine Operations, GeneralOffshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 10Chapter 1 Section 11.3.3 For novel designs, or unproved applications of designs where limited, or no direct experience exists,relevant analyses and model testing shall be performed which clearly demonstrate that an acceptable levelof safety can be obtained, i.e. safety level is not inferior to that obtained when applying this standard totraditional designs.
ReferenceTitleDNV-OS-H102Marine Operations, Design and FabricationDNV-OS-H201Load Transfer OperationsDNV-OS-H202Sea transport operations (VMO Standard – Part 2-2)DNV-OS-H203Transit and Positioning of Offshore UnitsDNV-OS-H204Offshore Installation Operations (VMO Standard Part 2-4)DNV-OS-H205Lifting Operations (VMO Standard - Part 2-5)DNV-OS-H206Loadout, transport and installation of subsea objects (VMO Standard - Part 2-6)Table 2 Other referencesReferenceTitleAPI RP 2ARecommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms - WorkingStress DesignAPI RP 2TPlanning, Designing and Constructing Tension Leg PlatformsAPI RP 2RRecommended Practice for Design, Rating and Testing of Marine Drilling Riser CouplingsAPI RP 2RDDesign of Marine Risers for Floating Production System and TLPsN-004NORSOK - Design of Steel StructuresAPI SPEC 2HSpecification for Carbon Manganese Steel Plate for Offshore Platform Tubular JointsAPI RP 2LRecommended Practice for Planning, Designing and Constructing Heliports for Fixed Offshore PlatformsBS 7910Guide on Methods for Assessing the Acceptability of Flaws in Fusion Welded StructuresBS 7448Fracture Mechanics Toughness TestsISO 19902Petroleum and natural gas industries - fixed steel offshore structuresEurocode 3Design of steel structures3 Definitions3.1 Verbal formsTable 3 Verbal formsTermDefinitionshallverbal form used to indicate requirements strictly to be followed in order to conform to the documentshouldverbal form used to indicate that among several possibilities one is recommended as particularly suitable,without mentioning or excluding others, or that a certain course of action is preferred but not necessarilyrequiredmayverbal form used to indicate a course of action permissible within the limits of the document3.2 TermsTable 4 TermsTermDefinitionheave restrained platform (HRP)a platform which is free to roll and pitch, but restrained in the heave eigenmodehigh frequency (HF) responsesdefined as TLP rigid body motions at, or near heave, roll and pitch eigenperiods dueto non-linear wave effectslow frequency (LF) responsesdefined as TLP rigid body non-linear motions at, or near surge, sway and yaweigenperiodsmini TLPsmall tension leg platform with one, or multiple columnsringingdefined as the non-linear high frequency resonant response induced by transientloads from high, steep wavesroll, pitch, and yawrotational modes around surge, sway and heave axis, respectivelyOffshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 11Chapter 1 Section 1Table 1 DNVGL and DNV reference documents (Continued)
TermDefinitionspringingdefined as the high frequency non-linear resonant response induced by cyclic(steady state) loads in low to moderate seastatessurge, sway, heavetranslatory displacements of TLP in horizontal planes (surge, sway) and verticalplane (heave)TLP deck structurethe structural arrangement provided for supporting the topside equipment ormodulesNormally, the deck serves the purpose of being the major structural component toensure that the pontoons, columns and deck act as one structural unit to resistenvironmental and gravity loads.TLP foundationdefined as those installations at, or in, the seafloor which serve as anchoring of thetendons and provides transfer of tendon loads to the foundation soilTLP hullconsists of buoyant columns, pontoons and intermediate structural bracings, asapplicableTLP tendon systemcomprises all components between, and including the top connection(s) to the hulland the bottom connection(s) to the foundation(s)Guidelines, control lines, umbilicals etc. for tendon service and or other permanentinstallation aids are considered to be included as part of the tendon systemvortex induced motions (VIM)vortex induced motion (VIM): Transverse (cross) and in-line, current induced floatermotionsvortex induced vibrations (VIV)the in-line and transverse oscillation of a tendon, riser, or floater in a currentinduced by the periodic shedding of vorticeswave frequency (WF) responsesTLP linear rigid body motions at the dominating wave periods4 Abbreviations and symbols4.1 AbbreviationsTable 5 AbbreviationsAbbreviationIn fullALSaccident limit statesAUTautomatic ultrasonic testingBTIbottom tendon interfaceBTCbottom tendon connectorDFFdesign fatigue factorsFLSfatigue limit statesFPSOfloating production storage and offloading unitHFhigh frequencyHRPheave restrained platformICinspection categoryLAJlength adjustment jointLATlowest astronomical tideLMPload management programOSoffshore standardOSSoffshore service specificationLFlow frequencyLRFDload and resistance factor designNDTnon-destructive testingQTFquadratic transfer functionRAOresponse amplitude operatorOffshore standard, DNVGL-OS-C105 – Edition July 2015Structural design of TLPs - LRFD methodDNV GL ASPage 12Chapter 1 Section 1Table 4 Terms (Continued)
AbbreviationIn fullSIMOPsimultaneous operationTADtender assisted drillingTLPtension leg platformTLWPtension leg wellhead platformTTItop tendon interfaceTTMStendon tension monitoring systemULSultimate limit statesVIMvortex induced motionVIVvortex induced vibrationsWFwave frequencyChapter 1 Section 1Table 5 Abbreviations (Continued)4.2 Symbols4.2.1 The following Latin symbols are used:xDDFX(χ)HsNDTpload effectnumber of yearslong-term peak distributionsignificant wave heighttotal number of load effect maxima during D yearswave period.4.2.2 The following Greek symbols are used:γf,Dγf,Eγf,G,Qγmload factor for deformation loadsload factor for environmental loadsload factor for permanent and functional loadsmaterial factor.5 Description of the tendon system5.1 General5.1.1 Individual tendons are considered within this standard as being composed of three major parts:— interface at the platform— interface at the foundation (seafloor)— link between platform and foundation.In most cases, tendons will also have intermediate connections or couplings along their length, see Figure 2.5.1.2 Tendon components at the platform interface shall adequately perform the following main functions:— apply, monitor and adjust (if possible) a prescribed level of tension to the tendon— connect the tensioned tendon to the platform— transfer side loads and absorb bending moments or rotations of the tendon
Fo r requirements that are not specifica lly defined in API RP 2T, applicable requirements stated in this offshore standard shall be followed. 1.1.5 A Tension Leg Platform (TLP) is defined as a buoyant unit connected to a fixed foundation (or piles) by pre-tensioned tendons. The tendons are
DNVGL-RP-F113 Pipeline subsea repair DNVGL-RP-F203 Riser interference DNVGL-RP-F204 Riser fatigue DNVGL-RP-F205 Global performance analysis of deepwater floating structures DNVGL-RP-N101 Risk management in
* DNVGL Type Approval to DNVGL-ST-F101 and DNVGL-RP-F113 10. Scope of Technology Assessment Main connector based on DNVGL Type Approved gripping and sealing technology via burst test, external load te
API RP 2SK API RP 2SM API RP 2I DNVGL-OS-E301 DNVGL-OS-E302 DNVGL-OS-E303 DNVGL-OS-E304 Guidelines for Offshore Marine Operations (GOMO) MODU Mooring in Australian Tropical Waters Guidelines Page 12 of 55 3 RISK SCREENING 3.1 Introduction The purpose of this section is to provide guidance on
For generic qualification procedures for new technology and service specifications, see DNVGL-RP-A203 and DNVGL-DSS-401.These guidelines provides a specific qualification procedure for how to utilize DNVGL-RP-A203 for qualification of AM technologies. See App.C. 1.6 Definitions and abbreviations Table 1 Definitions Term Definition
DNV GL offshore standards contain technical requirements, principles and acceptance criteria related to classification of offshore units. . DNVGL-RP-B401 Cathodic protection design DNVGL-RP-C201 Buckling strength of plated structures D
Recommended practice, DNVGL-RP-G105 – Edition October 2015 Page 3 DNV GL AS CHANGES – CURRENT Changes – current General This document supersedes DNVGL-RP-0006, January 2014. Text affected by the main changes in this edition is highlighted in red colour. However, if the changes On 12 September 2013, DNV and GL merged to form DNV GL Group.File Size: 2MBPage Count: 77
DNVGL Type Approved for 10” to 26” pipes in carbon steel with a corrosion resistant alloy liner in maximum working . to DNVGL-ST-F101 for Submarine Pipelines and DNVGL-RP-F113 recommended practices for pipeline repair. Other standards can be considered if re
Abrasive water jet (AWJ) machining has been known for over 40 years. It was introduced, described and presented by Hashish [1]. It is often used to cut either semi-finished products or even final products, namely from plan-parallel plates of material. Nevertheless, applications of abrasive water jets for milling [2], turning [3], grinding [4] or polishing [5] are tested more and more often .
